Process of treating arsenical material.



n. ANDERSON, IR.

PROCESS OF TREATING ARSENICAL MATERIAL.

APPLICATION FILED FEB. 7. 1914. IIENEWED IuNE 6,1916.

A TTORNEY DUNCAN NDERSQN, JR., OF SAN FRANCISCO, CALIFRNIA.

'PROCESS OF TREATING ARSENCAL INIATERIAL.l

Specification of Letters atent.

Patented Sept.. l2, 15M@ Application filed February 7,l 1914, Serial No. 817,186. Renewed June 6, 1916. Serial No. 103,026.

To all iii/"tom t may concern llc it known that l, DUNCAN NnnnsoN, Jr a subject of the King ot' Sweden, residing at San l `rancisco, in the county of San Francisco and State of California, have invented new and useful improvements in Processes ol1 'lli-eating- Arsenical ltlaterial, of which the followingis a speciication.

The object of thc present invention to provide a process for recovering the valuable constituents of arsenical flue dust, or of other material of high arsenic content, that is already in, or that can, by roasting or otherwise, be brougl'it into, a condition in which sultliiric acid can combine with the constituent metals.

ln the drawing, the figure is a diagrammatic representation of my improved process.

ln practising this process the arsenical material is first sulfated Without alkaline bisuli'ate fusion by being thoroughly mixed with sulfuric acid slightly inexcess ol that necessary to combine with constituent substances with which sulturi'y acid can coinbine. This step ot' the process may be cheapened by subjectiingthe material to the action ot sulfurous gases with subsequent oxidation, thus diininishing the amount of sulfuric acid required. rlhe mass is then subjected to a gentle heat, with stirring, for such a length ot time that, when cold, the mass may be pulverized. The mass is then pulverined by rolls or other suitable means, and transferred to'a liuc or hearth, maintained at an even heat, above the boiling point of sulfuric acid and below the point oi.2 decomposition of the metallic sultates, and in al current of air or gas. It" air is used,

arsenic is volatilized in combination Withsuliuric acid, and can be precipitated by Water spray, or by electric precipitation in a condensing chamber beyond. .lhis separation depends on the :tact that the sulfuric treated to recover the 'valuablebretels.l lt'- is first roasted until the sulfate of iron, which is generally present, .is partly decomposed, and the material becomes' of a light pinlr color. rlhe mass is then leached with hot water, by which such sulfates as those of Zn, Cd, Cu, Fe, Ag, Bi, are dissolved out together with small amounts of arsenic and antimony. T he residue is filter-pressed and washed. lt contains any lead sulfate that may have been formed, most ofv the. antimony and bismuth, and considerable of the arsenic remaining after the first treatment, and is suitable for treatment for lead' by well known metallurgical methods. The solution-is treated with zinc dust, whereby Cd, Cu, etc., 'with probably small amounts ol As'Sb, are precipitated. The metals are separated from solution by any suitable means, and the solution is treated'with an oxidizing agent, such as a peroxid or perslllfate, to oxidize the iron, arsenic, etc., and is treated with lime, zinc oXid, or other basic material, to precipitate the iron and the remaining arsenic and antimony. The zinc sulfate can be crystallized out and roasted for Zinc distillations, or otherwise utilized.

l. 'In the recovery of metals from arsenical material suchas flue dust and arsenical ores, the process which consists in the addition of sulfuric acid, in ambuntnot greatly exceeding that required for combination with the substances present, calculatinnr for basesv that required to form normal salts, and heating' to drive otf arseni from solids resulting therefrom.

9,. ln the recovery of metals from arsenical materials containing iron and zinc such as flue dust and arsenical ores, the process which consists in the addition of sulfuric acid, in amount not 2greatly exceedingr that required for combination with the substance present, calculating for bases,that required to orm normal salts. heating; to drive ott arsenic Jfrom solids resulting,r therefrom, roasting' at such temperature that no incre than a small amount of zinc .is renderedinsoluble, and finally dissolving out soluble materials with vater,

3. In the recovery ot' metals from'arsenical material such as flue dust and arsenical ores, the process which consists in adding,v sulfuric acid by contact with sulfur-ous gases previously passed over contact material, in amount not' greatly exceeding that required forcoinbination with the that required t0- form heating to drive off arsenic from solids resubstances present, calculating for bases vnormal salts, and

Sultin' therefrom.

4. n. the treatment of arsenic carrying su1fates, containing iron and zinc, to recoverv metals, the process which consists yin roastlng' to decompose lron sulfates to oxxdlze lron to render arsemc lnsoluble, and

vthen dssolvingut the soluble contituonts 10 

